In the beginning, in dimension filled with life energy, called Zone Energy, there was only one Spark (or Lasercore), spawned from primal energies of that plane. The Original Spark (or Lasercore) had the ability to merge with any machine and become its central nervous system in order to give that machine life.
The most powerful of the benevolent sparks was found by an alien named Primacron.
Primacom had develope a special project
a small planetoid that would fuel itself off of space debris, called Unicron ,that could also transform into a robot as well.
Primacron, unaware of the dark spark's existence, sees Unicron transform of its own accord. Primacron tries to override his creation, but to no avail.
Millions of years passed. Unicron grew larger & larger with every meal. While journeying across the Galaxy, devouring planet after planet.